The present invention relates to a microfluid system comprising at least one flow-through volume and at least one connection means connected to the volume, and to a plug means for use in such a microfluid system.
Microfluid or microfluidic systems show high potential in analysis and diagnostics in biological and medical applications. Moreover, they can be used for the synthesis of chemical and biological products, for example as flow reactors.
Microfluidic systems are characterized in that very small amounts of liquid media are transported in small structures. The liquid volume ranges here from 10 ml to less than 1 nl. A clear trend in microfluidics is that individual components are to be interconnected by special connections to obtain a whole system. Apart from the interconnection of microfluidic components, it is particularly the connection to the macroscopic world that poses a great challenge. Due to the miniaturized structural dimensions, which are normally between nanometers and millimeters, special demands are made on the connections.
These demands are: easy connection and disconnection of the connections; high stability with respect to unintended disconnection; high density with respect to gas and liquid exchange; small dead volumes in relation to the volume of the microfluidic components; preventing the penetration of undesired air when the connection is established (air bubbles), guaranteeing sterile conditions. Moreover, the connections should be biocompatible and possibly transparent to be able to check, for example, whether the medium actually flows through the structure. The solution should be parallelizable and advantageous in terms of production.
There exist numerous apparatuses designated as microfluidic systems.
U.S. Pat. No. 5,170,286 (WO 9215037) discloses, for instance, an observation chamber for microscopy in combination with a connected flow system. This is a “sandwich” construction that consists essentially of a special mounting (‘central chamber element’) into which microscopy cover glasses are inserted, the glasses being fixed by cover plates. Throughflow must be generated in this chamber through hose connections to a reservoir, which is not mounted on the chamber. No information is furnished about the connections, especially their properties such as stability, tightness, easy handling, dead volumes, etc. Nor is it described how this can be guaranteed with respect to the connection geometry.
WO 97/38300 describes a microchannel system of acryl that serves electrophoretic separation. The microchannel, however, is not used for flushing liquid therethrough. This document is also silent about the connection geometry with respect to the said demands.
WO 90/05295 also describes an optical biosensor system with channels. The liquid to be analyzed is passed on by means of valves and pumps. The document is also silent about any special geometry of the connections and special types of the connections for solving said problems.
DE 197 11 281 C21 also describes an apparatus with microfluid components. This patent specification places emphasis on the arrangement and integration of the functional layers in the carrier. It is in general silent about the geometry of the connections.
The said documents are silent about cover systems which close the flow chambers and contain special integrated components.
It is therefore not known from the prior art concerned with microfluid systems how the above-mentioned properties of connections and terminals are to be realized.
Although formerly existing connections for filling gases or liquids, e.g. hose clamps, efficiently prevent gases and liquids from exiting, they are very difficult to handle in a miniaturized form. The standardized connections known from medical engineering (Din-Taschenbuch 227, Medizinische Einmalartikel, Vertikale Normen Beuth Verlag 1999) have in general a dead volume that is much too large in relation to the total volume. As a consequence, it is above all impossible to handle small sample amounts. Moreover, the plug connections as shown there are not intended or optimized for use with microfluidic components, such as planar flow chambers. With many applications, the use of screw plugs contradicts the demand that a liquid should be adapted to be filled rapidly into a channel. These screw plugs, however, can and are used for tightly closing, for instance, flow chambers. Moreover, glued connections are not suited for analysis chips that can only be used once.